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U35/59 Wollongong St
PO Box 1265, Fyshwick ACT 2609
Ph: 02 6280 4700 : 02 6280 4775
Email: tech@auf.asn.au
15 May 2001
13 June 2001
MAINTENANCE ALERT: GSC PROP - TOWNSVILLE ACCIDENT
There was an accident in May 2001 to a Lightwing in the Townsville area caused by a blade breaking off at the hub
of a GSC propeller. The two ladies in the aircraft suffered minor injuries
or were shaken, but my spy advises that the pilot was quickly in the air
again and the other has flown since also. Well done.
These GSC propellers consist of wooden blades with
special composite or aluminium ends which are retained by clamping between
the hub plates. There is also a through bolt which passes though the blade
root.
In the case in question, the through bolt was very
badly corroded and the material of the blade was badly discoloured
suggesting that the moisture which caused the corrosion had also commenced
to reduce the integrity of the wooden blade material itself (it was
apparently going rotten!).
The wooden blades of these propellers are bonded (glued) into the
socket and it is the outside of this socket which is clamped by the hub
clamping bolts. (See Photographs below). As a safety measure, a bolt
passes through the socket and through the root of the blade and seems to
be intended as a retaining pin if the bonding (glue) holding the blade
into the socket failed or if the clamping on the socket was faulty.
The design assumes that the wood of the blade root is sound.
Thanks to Egovision Studios in Canberra and their voluntary
photographic services,
 the two photographs above clearly show what remains
of the defective blade and of the corroded bolt.
The first at Figure 1 is a good illustration of how the wooden root has
just pulled out of the socket leaving the fibres which had been penetrated
by the glue in place still glued to the socket.
The second at Figure 2 clearly shows the rusty bolt and
the plug of deteriorated wood it prevented from pulling out and it shows
another view of the surface wood of the blade glued to the inside of the
socket. The only value of the bolt in the case of a faulty blade root is
to prevent the socket from departing with the blade: no use at all if the
rest of the blade is faulty. It doesn't matter how good the glue is or how
secure the bolt is - if the wood is faulty, the blade will separate.
Action Recommended.
Operators of these propellers are
advised to assess whether the propellers should be disassembled for
inspection. One obvious indicator would be to remove the through bolts to
check their surface condition. However, if these bolts have been replaced
during the life of a propeller, they may be in good condition yet the
material of the blades which would have been subject to the environment
for the full life of the blades may not necessarily be the same.
Signs of advanced problems may be
evident where the blade exits the plastic socket but it would be necessary
to disassemble the propeller to be really sure.
GSC SYSTEMS
a
division of A.S.A.P.
6255 Okanagan Landing Road
Mail Box 995 Vernon, B.C. V1T 6Y5
PHONE: (250) 549-3772
: (250) 549-3769
May
17, 1999
GSC SYSTEMS SERVICE BULLETIN
AFFECTED
MODELS All GSC Systems 2 and 3 blade ground adjustable
GSC
Systems has been in the business of producing quality props for over
15 years for many types of aircraft. Over the course of these 15
years, it is possible that the original aircraft and/or the GSC
propeller may have changed ownership several times. During the
transfer of ownership often the instructions and maintenance
procedures of our propellers have been lost. To that end, many
propellers receive incorrect maintenance.
The
most critical assembly procedures of our propellers are that the hub
and root ends not be tighten past the recommended 100 in/lb
torque specification. It is also possible that due to the over
tightening of the attach bolts, that the space between the aluminum
hub halves is no longer visible. The result of this improper assembly
or maintenance could result in premature blade failure resulting in
either injury or death.
If
you do not presently have a set of GSC assembly instructions please
contact GSC Systems and one will be forwarded to you.
REQUIRED SERVICE Immediate inspection
1.
Inspect to insure that a visible gap between the Aluminum hub
halves is detected. If no gap is visible contact GSC Systems.
2.
If you are the initial and original owner of a GSC Propeller,
are you certain that the hub has never been torqued past the 100 in/lb
MAX torque specification, if not contact GSC Systems.
3.
If you are not the original owner of a GSC propeller can you be
assured that the GSC propeller hub has never been torqued past the
100in/lb Max torque specification, if not contact GSC Systems.
GSC SYTEMS TBO
GSC
systems have documented user times of over 1000 hours but due to the
nature of the exchange and selling of our product we are implementing
a 500 or 5 year TBO for all GSC propellers.
If
you require further information please feel free to contact GSC
Systems. Our goal is to continue the supply of a quality and safe
product.
GSC SYSTEMS
a
division of A.S.A.P.
6255 Okanagan Landing Road
Mail Box 995 Vernon, B.C. V1T 6Y5
PHONE: (250) 549-3772
: (250) 549-3769 |
